SOME CHEMICAL CONCEPTS 133 



the soil are in this way neutralized. Thus one would 

 get the equation : 



H H H 



/) TT\ /& IT H\ 



Hr* f^js . n\-.T /-\ TT TT /-* fij^ t ** i- No 



U L/v ~r TT /-tN \J ri = n \~> v>\ 



I X OH 7 I - _ 



H H V H 



Acetic Acid. Ammonia. Ammonium Acetate. Water. 



Base. Neutral, 



In conclusion, a few definitions may prove useful : 



A CARBOHYDRATE is a compound of Carbon, 

 Hydrogen, and Oxygen, the two latter elements 

 being present in the same proportions as they are 

 present in water. To this class belong the various 

 celluloses, starches, and sugars. 



PROTEINS. These all contain Carbon, Hydrogen, 

 Oxygen, and Nitrogen. Phosphorus, Sulphur, and 

 a few other elements are also often present. It is a 

 characteristic of the class that the molecule is large, 

 and contains a number of complex groupings. 



FATS. These are neutral bodies consisting of a 

 combination of Glycerine and the so-called Fatty 

 Acids i.e., acids of the Formic and Acetic Acid 

 group, which has C n H 2n O 2 as the common formula 

 of the group, n being any whole number. 



AMIDES. These enter largely into decomposition 

 and other changes. They may be regarded as 

 derivatives of Ammonia (NH 3 ). They are written 

 /H, 



place of simply attached Hydrogen in organic com- 

 pounds. Their importance in Nature may be 



